In today's modern railroad industry, it is well known that couplers are used to connect adjacent ends of a pair of railway cars together. On any of these railway cars which will possibly be used in interchange service, these standard couplers must have received approval by the Association of American Railroads (AAR) prior to their installation on such railway cars. It is generally well recognized that, in this application, such couplers are required to serve a number of functions in addition to facilitating the connection and disconnection of individual railway cars to and from, respectively, a train consist. One of these additional functions, for example, is to enable such individual railway cars to successfully negotiate the curved portions of a track encountered in the track structure. Additionally, such standard couplers enable such railway cars to be easily and readily combined so that a train consist can be made up. Further, when necessary, such couplers allow such railway cars to be readily separated into individual cars for either loading or unloading cargo thereto or therefrom, respectively.
However, in more recent times, it has come to be generally recognized in the railroad industry that a significant number of rather important advantages can be achieved by the interconnection of a number of railway cars to form a substantially semi-permanent unit. This is particularly the situation, for example, where such railway cars are specifically designed for use in what is known in the industry as "piggyback" or intermodal service. The reason for this is that the cargo to be either loaded or unloaded is brought to or removed from, respectively, predetermined locations. Such cargo is usually over-the-road trailers or large containers. The individual railroad cars which have been joined together in this substantially semi-permanent manner are commonly known in the railroad industry as a "10-pack". Except at the extreme outer ends of each 10-pack unit, these 10-pack units do not require the use of the standard couplers discussed above. The primary reason why such standard couplers are not required in this application is because of their dedicated service, these 10-pack units are broken only on a periodic basis. For example, in most cases, this will normally only occur when some maintenance must be carried out on either an individual coupler component or some other critical component positioned on the railway car which will require an individual car to be taken out of service on a temporary basis.
It has become obvious to the railroad industry that with the use of this semi-permanent coupling arrangement it is possible to achieve a significant reduction in costs. These cost reductions can be attributed to a variety of reasons. At a minimum, these reasons include a reduction in the weight of the equipment. Such weight reduction results in a significant reduction in energy requirements. In addition, because fewer railway trucks are required, this results in not only reduced equipment costs but also results in a reduction of maintenance requirements.
Now, however, with the rather extensive use of these semi-permanent coupling arrangements and with the ever increasing loads that must be carried by modern railway cars and train consists, the railroad industry and railway equipment suppliers have determined that it is of critical importance for a close-buttoned relationship to be maintained between the coupler draft components present in a particular coupling arrangement. Such close-buttoned relationship has been found necessary, for example, so that the detrimental effects of impact forces which are encountered during normal train operation can be reduced to an acceptable level. In this manner, damage incurred to both cargo and equipment can be held to an absolute minimum. Such impact forces are normally encountered during normal buff operations of the train.
With the above discussion in mind, attention is directed to one prior art type articulated coupling arrangement used for the purpose of connecting adjacent ends of a pair of railway cars together in such semi-permanent fashion. This prior art coupling device is taught in U.S. Pat. No. 4,258,628. As is shown therein, this particular articulated coupling apparatus includes a male connection member secured at one end thereof to one end of a first railway car body member and a female connection member which is secured at one end thereof to an adjacent end of a second railway car body member.
In this prior art coupling arrangement, the female connection member is rotatably engaged in a center plate bowl portion of the bolster member of the railway truck member. This rotatable type engagement is accomplished in a manner that is generally well known in the railway art. The male connection member is disposed for movement, at the outer end portion thereof, within a cavity located in the outer end portion of such female connection member. In this coupling arrangement, a pin member is utilized to connect both the male connection member and the female connection member together in such substantially semi-permanent fashion. This pin member is positioned in a vertical direction and is disposed in aligned apertures which are formed in each of such male connection member and such female connection member. It is important to note that, as is taught in this reference, the aperture formed in such male connection member for receiving the pin member therein must be formed somewhat larger than the pin member itself. This is necessary in this arrangement to enable certain movements required of the coupling apparatus to be achieved during in-track service. Additionally, it should be noted that a rear surface portion of such aperture formed in such male connection member and which will receive such pin member therein includes a horizontally disposed concave configuration and a vertically disposed convex configuration. This particular configuration is desirable so that both the male connection member and the female connection member can move in each of a horizontal direction and a vertical direction with respect to one another. At the same time, this configuration provides a rather substantial area of surface contact between the rear surface of the pin aperture and the pin member itself.
The outer end surface of the outer end portion of such male connection member includes a convex configuration which abuttingly engages a complimentary concave surface which is formed on a front face portion of a follower member. The follower member, in this coupling arrangement, is disposed within the rear portion of such cavity located in the outer end portion of such female connection member. The rear face portion of such follower member includes a pair of vertically-disposed slot-like cavities formed therein. A first portion of a resilient member is disposed within each of these vertical slot-like cavities. A second portion of each such resilient member extends outwardly from such rear face portion of such follower member. In this manner, a vertically disposed wedge-like element can be engaged with such exposed outer surface area of each such resilient element. Such wedge-like element being a necessary component of this coupling arrangement so that during service the follower member and the male connection member can be urged forward. Consequently, the rear surface portion of the aperture formed in the outer end of the male connection member is maintained substantially in contact with the pin member at all times.
Because most of the articulated connecting members used in this coupling arrangement are normally manufactured as cast components, such contact being maintained between the pin member and the rear surface portion of this aperture in the male connection member is essential. Furthermore, in order to maintain the production costs of this coupling apparatus as low as possible, such cast components will receive very little, if any, finish machining to provide either the necessary or the desirable dimensional control. These cast components, in other words, are generally used as cast. It is quite often difficult, as a result of this cost-saving practice, to provide an articulated coupling apparatus which will be self-adjusting under the various wear conditions which such coupling apparatus will normally encounter during operation. Nevertheless, it is important to minimize as much as possible the slack encountered in the various coupling connections during such in track service.
Other prior art coupling devices are taught in U.S. Pat. No. 3,716,146 and Canadian Patent Number 1,231,078.